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Replacing a Zip file without unzipping in Java

I have a zip file and I want to replace one file inside it with another file. So do not need to delete a zip entry just replace the file for the zip entry with another.
Here is what I have tried.
public void replaceConfigurationFile(ZipFile zipFile, ZipOutputStream zos, String pathToNewFile, String configFileToReplaced)
throws IOException {
String zipEntryName;
for(Enumeration<?> e = zipFile.entries(); e.hasMoreElements(); ) {
ZipEntry entryIn = (ZipEntry) e.nextElement();
zipEntryName = entryIn.getName();
if(zipEntryName.endsWith(configFileToReplaced)) {
FileInputStream fis = new FileInputStream(pathToNewFile);
ZipEntry zipEntry = new ZipEntry(zipEntryName);
zos.putNextEntry(zipEntry);
byte[] bytes = new byte[1024];
int length;
while ((length = fis.read(bytes)) >= 0) {
zos.write(bytes, 0, length);
}
zos.closeEntry();
fis.close();
} else {
zos.putNextEntry(entryIn);
InputStream is = zipFile.getInputStream(entryIn);
byte [] buf = new byte[1024];
int len;
while((len = (is.read(buf))) > 0) {
zos.write(buf, 0, len);
}
zos.closeEntry();
}
} // enf of for
}
I have a file zip Entry named :
WEB-INF/classes/config/app-dev.yml
and I have a file at location d drive at location
D:/app-dev.yml
I am able to copy the file in to a different zip file by replacing the file i want to replace . But that is really not needed (to create a different file).
So what should I do to just replace the file with my custom file.
I have searched different posts in Stackoverflow, but unable to find what i need. I read that zip entry cannot be deleted but what about replacing it ? Please help

Your problem is that the new file might be larger than the old file - or smaller! You need to do exactly what you did to allow for the change. The probability that the new file, ZIPped, is exactly the same size as the previous one is virtually nil.

The standard Java ZIP file libraries do not allow you to update an existing ZIP file. You need to use a third party library. A Google search should find you a number of alternatives.
But you need to be aware of a couple of things:
If your application ... or system ... crashes while updating the ZIP file, the file may be corrupted.
When a ZIP file is updated, the replacement version of the file will be appended to the ZIP. The old version of the will still be in the ZIP ... but not in the ZIP file index. Hence updating a ZIP file (without rewriting it) wastes disk space.

Extract files from *.gz extension

I have successfully extracted *.gz from *.tgz and now I have no idea how to actually extract final files from *.tgz.
There are some options using custom packages but that's not an option for me, I need to use standard Java packages only.
What I tried is using same function that I use for *.tgz for *.gz but it doesn't work.
java.util.zip.ZipException: Not in GZIP format 1.gz
Here is function that is extracting *.tgz files.
public String ExtractFile(String path) {
try {
File newFile = new File(this.getFullPathWithoutExtension(path) + ".gz");
GZIPInputStream gStream;
FileOutputStream outStream;
try (FileInputStream fileStream = new FileInputStream(path)) {
gStream = new GZIPInputStream(fileStream);
outStream = new FileOutputStream(newFile);
byte[] buf = new byte[1024];
int len;
while ((len = gStream.read(buf)) > 0) {
outStream.write(buf, 0, len);
}
}
gStream.close();
outStream.close();
newFile.createNewFile();
return newFile.getPath();
} catch (Exception e) {
System.out.print(e);
}
return null;
}
TL;DR; *.tgz files extracted to *.gz files, however *.gz files cannot be extracted.

A .tgz file wouldn't normally be extracted to a .gz file - it would be extracted to a .tar file. (A .gz file is gzipped; a .tar file is an uncompressed archive containing multiple files; a .tgz is a .tar file that's then been gzipped - you've already "undone" the gzipping.)
I don't think there's anything within Java's standard libraries to handle tar files - so you'll either have to revisit your "I can't use anything not in the standard library" decision or reimplement it yourself. The file format is easily available if you decide to do that.

ZIP file created using Java showing empty when open with Windows Explorer

The below code is used to zip normal text file. When I extract using WinRaR its showing the content properly, but when I open with Windows Explorer its empty, no file listed. I am using Windows 7 Enterprise (64 bit) operating system. Any idea why its not listing in Windows explorer? Thanks in advance.
File file = new File("F:\\sample.txt");
byte[] buf = new byte[1024];
String outFilename = "F:\\zipped_sample.zip";
try {
ZipOutputStream out = new ZipOutputStream(new FileOutputStream(outFilename));
FileInputStream in = new FileInputStream(file);
out.putNextEntry(new ZipEntry(file.toString()));
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
out.flush();
}
out.closeEntry();
out.close();
in.close();
} catch (Exception e) {
// log exception here
}

ZipEntry constructor takes name but you are providing it a path by doing file.toString(); Try:
New ZipEntry(file.getName());
This will pass the file name.

i had the same problem zip file were not extracted and was shown as empty the problem was in the folder names in zip file. If folder name consist of > or < symbols i saw the failure . SO in the code new ZipEntry(file.toString()) i try to clean up any folder names with those particular symbols

Zipping Files using util.zip No directory

I have the following situation:
I am able to zip my files with the following method:
public boolean generateZip(){
byte[] application = new byte[100000];
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// These are the files to include in the ZIP file
String[] filenames = new String[]{"/subdirectory/index.html", "/subdirectory/webindex.html"};
// Create a buffer for reading the files
try {
// Create the ZIP file
ZipOutputStream out = new ZipOutputStream(baos);
// Compress the files
for (int i=0; i<filenames.length; i++) {
byte[] filedata = VirtualFile.fromRelativePath(filenames[i]).content();
ByteArrayInputStream in = new ByteArrayInputStream(filedata);
// Add ZIP entry to output stream.
out.putNextEntry(new ZipEntry(filenames[i]));
// Transfer bytes from the file to the ZIP file
int len;
while ((len = in.read(application)) > 0) {
out.write(application, 0, len);
}
// Complete the entry
out.closeEntry();
in.close();
}
// Complete the ZIP file
out.close();
} catch (IOException e) {
System.out.println("There was an error generating ZIP.");
e.printStackTrace();
}
downloadzip(baos.toByteArray());
}
This works perfectly and I can download the xy.zip which contains the following directory and file structure:
subdirectory/
----index.html
----webindex.html
My aim is to completely leave out the subdirectory and the zip should only contain the two files. Is there any way to achieve this?
(I am using Java on Google App Engine).
Thanks in advance

If you are sure the files contained in the filenames array are unique if you leave out the directory, change your line for constructing ZipEntrys:
String zipEntryName = new File(filenames[i]).getName();
out.putNextEntry(new ZipEntry(zipEntryName));
This uses java.io.File#getName()

You can use Apache Commons io to list all your files, then read them to an InputStream
Replace the line below
String[] filenames = new String[]{"/subdirectory/index.html", "/subdirectory/webindex.html"}
with the following
Collection<File> files = FileUtils.listFiles(new File("/subdirectory"), new String[]{"html"}, true);
for (File file : files)
{
FileInputStream fileStream = new FileInputStream(file);
byte[] filedata = IOUtils.toByteArray(fileStream);
//From here you can proceed with your zipping.
}
Let me know if you have issues.

You could use the isDirectory() method on VirtualFile

Putting a Folder in a Zip in Java

I am having an issue putting a folder in a zip file I am trying to create. While the path is valid, when I run the code it gives me a File Not Found Exception.
Here is my code
String outFilename = "outfile.zip";
ZipOutputStream out = new ZipOutputStream(new FileOutputStream(outFilename));
byte[] buf = new byte[1024];
File file = new File("workspace");
System.out.println(file.isDirectory());
System.out.println(file.getAbsolutePath());
FileInputStream in = new FileInputStream(file.getAbsolutePath());
out.putNextEntry(new ZipEntry(file.getAbsolutePath()));
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
out.closeEntry();
in.close();

You're trying to read bytes from a directory; it doesn't work like that. The exception says as much, too.
You need to add the directory, then add each file within the directory. If you use the file path you don't need to add the directory explicitly.
I'd be very wary of using the absolute path as the zip entry; better to use a relative path so you can unzip it anywhere and not risk overwriting something you want.